It won't man. Coral eat the same food algae does. If there at too much algae grows. You don't have any. I have a sumples tank with a skier that half works. I have high N/p. I have very little alge and no Cyano I also have a coral qt w rock Dsb and no fish that I don't hardly Feed The nutrients have completely bottomed out. Cuz I have the prob you are worried about. Bacteria has eaten all the food. All you can do is try. Pull one block And many try whit I suggested. We've cured a lot of Dino's with that method. Then keep slowly escalating. Slowly. One of the next steps , a pain in the bit imo. No3 dosing to cure the N limitation prob. But that as you say makes you think you'll grow alge too. Honesty were it my tank , I'd hook up the canister , pull all the rock empty the sump. Go back to the kiss method (Berlin ) scrub the rock w peroxide and re start. Prob take me a day. I'd also throw a can of Fiji mud in and make a mes , toss some chato in the fuge old school and over feed the tank for months to create a forced maturity. Then over months let the nutints drop back to normal and keep buying coral the whole time. That way in six or eight months the tank will be rocking. But that's me.